Bacterial Meningitis

Preventive Pearls

The spread of some types of bacterial meningitis can be prevented by administering prophylactic antimicrobials to contacts of patients with bacterial meningitis. The means by which chemoprophylaxis prevents secondary disease is by preventing transmission of the bacteria to susceptible hosts and by eradicating the organism from the nasopharynx of those who are already colonized.[28] Such therapy is recommended for close contacts of patients infected with H influenzae or N meningitidis. In general, close contacts are defined as household or day-care members who sleep or eat in the same dwelling as the index patient. Therefore, health care workers do not require chemoprophylaxis unless close contact with the patient's secretions occurs, as in mouth-to-mouth resuscitation.

For contacts of patients with H influenzae meningitis, the chemoprophylactic agent of choice is rifampin at a dosage of 10 mg/kg twice a day (maximum, 1200 mg/d) for 4 days. For contacts of patients with N meningitidis meningitis, rifampin is also used, but the duration of therapy is only 2 days. An alternative to rifampin for adult contacts of patients with meningococcal meningitis is a single 500-mg dose of ciprofloxacin. Rifampin and ciprofloxacin are both contraindicated in pregnant women; the agent of choice in this population is a single 250-mg dose of intramuscular ceftriaxone. Since penicillin, ampicillin, and chloramphenicol do not reliably eradicate nasopharyngeal colonization with H influenzae or N meningitidis,[29] index patients who are treated with one of these agents should subsequently receive one of the above chemotherapeutic regimens.

Immunoprophylaxis against specific pathogens is a useful means of decreasing the incidence of bacterial meningitis. As noted earlier, incorporation of the H influenzae type b conjugate vaccine into the routine immunization schedule for children has resulted in a 94% decline in the number of cases of meningitis from this pathogen in the United States.

Vaccination with the quadrivalent (active against serogroups A, C, Y, and W135) meningococcal vaccine is recommended for certain high-risk populations, including those with terminal complement component or properdin deficiency, asplenic patients, persons traveling to areas known to have hyperendemic or epidemic meningococcal disease, dormitory-dwelling college students, and military recruits. This vaccine's utility as an adjunct to chemoprophylaxis for close contacts of an index patient is unproven. There is no good vaccine available in the United States to protect against serogroup B meningococcal disease.

One final comment is needed regarding the current pneumococcal vaccines. The 23-valent pneumococcal vaccine is recommended for the prevention of bacteremic pneumococcal disease, and while the vaccine's ability to prevent meningeal disease is unproved, its overall efficacy against pneumococcal meningitis is assumed to be about 50%.[30] The efficacy of the heptavalent pneumococcal conjugate vaccine has been studied prospectively in large numbers of children.[31] Results show 97.4% efficacy in preventing invasive pneumococcal disease, including meningitis, from the 7 serotypes of pneumococci in the vaccine and 93.9% efficacy in preventing invasive disease from all pneumococcal serotypes.